just like the man said above...what are you wanting to build with this 400..i agree with the rest of the guys that the 4 bolt (3) freeze plug 400 is the weakest (webbing etc)....However i have seen these blocks handle 600 hp ..NO PROBLEMS !!!...i have owned several of these blocks and ran the DOG SNOT out of them....turning 7200 rpm......NO I WOULD NOT try to make it some high hp spray or blower motor...but i would not hesistat to run 600-650 ponies with this block....
If you have blocked filled that (2) freeze plug 400 block of yours..i would not hestitate to run it and go over 700 hp with it..i personally think you would have a better drag motor than the 350 block......my opinion only...
Brian
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Bjuice..
"I'M YOUR HUCKLEBERRY ! "